TCS Synthesis

In the 1950s, Union Carbide, Dow Chemical, and Wacker Chemie all developed TCS production processes to supply the polysilicon industry. The main chemical reaction for TCS synthesis occurs between metallurgical grade silicon (MGSi) and hydrogen chloride (HCl). This process is called hydrochlorination.

PPP has made numerous process improvements to TCS synthesis to increase yield and uptime and also provide highly efficient production equipment. TCS is made from MGSi and HCl according to the reaction:

MGSi + 3 HCl  →  SiHCl₃ + H₂

MG silicon, in the form of particles, is fluidized in a fluidized bed reactor (FBR) and is reacted with anhydrous HCl. Historically, high efficiency production of TCS for solar grade polysilicon (SOG) applications has been constrained by the high heat of reaction between MGSi and anhydrous HCl. This highly exothermic reaction proceeds rapidly at the operating conditions of the FBR and, if uncontrolled, can create localized heating. In addition to damaging the FBR vessel and its components, high temperatures result in the generation of by-product STC and frequent shutdown and maintenance of the FBR, which is a very frequent occurrence in TCS production.

PPP’s design concentrates on control of this exothermic reaction, through a combination of PPP’s proprietary and patent pending technologies, to provide high yield of TCS and maximum production. Effective use of PPP’s FBR reactor and process technologies will decrease the need for frequent shutdown and maintenance which have plagued other FBRs.

Advantages of PPP's Advanced Hydrochlorination Process

• Stabilized temperature in fluidized bed reactor maximizes production
• High conversion of MGSi to TCS
• Single fluidized bed reactor generates sufficient TCS to supply a polysilicon plant
• Lower operating temperature and pressure
• High uptime